Hi
We’ve done it for the last 3 years, different routes each time. If I was doing it for the first time, I’d go train to Calais, Belgium, France, Luxenbourg (cheap fuel), France, Switzerland (Gottard Pass or tunnel). You can comfortably do that with 3/4 nights stopover on the way.
From Switzerland into northern Italy, stay a night or two by the lakes, any will do, they’re all wonderful. Auto-Strada all the way down to Ancona, this is the only stressful part of the journey, the Italians have crazy attitude to driving.
Enjoy.
You can mostly steer clear of toll roads until the e40 it costs to go though Switzerland, you will pay on the Auto-Strada also.